Electrical connector



1944- R. w. CARLISLE ET AL 7 2,339,146

ELECTRICAL CONNECTOR Filed July 18, 1940 2 Sheets-Sheet 1 3*1 rm $4011 J 22 J 2 8 INVENTOR fimCa cfiofewndqzkmmhopdq BY ATTORNEY 1944- R. w. CARLISLE El'AL 2,339,145

ELECTRICAL CONNECTOR Filed July 18, 1940 2 Sheets-Sheet 2 INVENTOR ATTORNEY l'atented Jan. 11 1944 zs'saus ELECTRICAL CONNECTOR Richard w. Carlisle, Elmsiord, and Alfred J. Mastropole. New York, TN. 1 assignors to Sonotonc Corporation, Elmsi'ord, N. Y., a corporation of New York Application July 18,1940, Serial No. 346,112

10 Claims.

This invention relates to electrical connectors. and particularly to electrical connectors for devices, such as hearing aid devices, which are 'iormed of several operating units that are small enough for inconspicuous wear' on the body of the user and have to be interconnected by electrical cords for completing the operating circuits between the'several units.

Among the objects of the invention is an improved electrical connector of the foregoing type which is electrically more eillclent in completing the electric circuits and exhibits mechanically a much higher degree of ruggedness. simplicity and otheradvantages, not found in prior connectors.

The foregoing and other objects of the invention will be best understood fromfthe. following description of exemplincations thereof, reference being had to the accompanying drawings wherein Fig. 1 illustrates a hearing aid earphone worn in the ear of the user equipped with connectors of the invention;

Fig. 2 illustrates the earphone of Fig. 1 with parts broken away to illustrate the arrangement of one form of a plug-Jack connector oi the invention; I I

Fig. 3 is a view along line 1-3 of Fig. 2: Fig. 4 is an enlarged view of a casing portion of Fig. 8 with the connector mounted therein: Fig. 5 is a view along line l-l of Fig. 4; Fig. '6 is a view similar to Fig. 4 of a modified form of connector of the invention:

Fig. 7 is an elevational view of the spring oi Fig. 0;

Fig. 8 is a view along line 8-1 of Fig. 6; Fig. 9 is a view similar to Fig. 2 illustrating another arrangement of the connector of the invention:

Fig. 10 is a view along line ll-ll of Fig. 9: I Fig. 11 is a view of the earphone of Figs. 9 and 10;

Fig. 12 is a cross-sectional view through a plug having connectors oi theinvention;

Fig. 13 is a view along line lS-ll of Fig. 12; Fig. 14 is an enlarged partially sectional view of a connector element of the plug shown in Figs. 12 and 13; v v

Fig. 14A is a view along line llA-HA of Fig.

Fig. 15 is a view along line ll ll of Fig. 13: Fig. 16 is a perspective view of the connector shown in Fig. 14;. I

Fig. 17 is an, elevational view of a plug forming part of the connector shown in Fig. 2; and Figs-18 to 20 are partially elevational and par tially sectional views illustrating successive steps 56 is in mounting the connector of Figs. 16 and 17 on its cord.

Most oi the deafened are very sensitive and seek to conceal their hearing impairment. Accordingly, a satisiactory hearing aid device for suppLving the, deafened person with the sound energy required to overcome his handicap must be suitable for comfortable and inconspicuous wear and simple and foolproof in operation so as to free the user from physical as well as mental strains. All the elements of the device must not only be small and light in weight, but must be able to respond at high eillciency to all important speech frequencies and they must operate satisfactorily under all conditions of use, without special attention and frequent reconditioning.

A most important consideration in the design of hearing aids is that they be as inconspicuous and as comfortable as possible. For instance, the midget earphone or receiver forming a part of such hearing aid 'has to be made extremely small so as to make it possible to hold it flush within the lobe of the ear in the wag shown in Fig. 1. This requires that its thickness should not be more than .3 of an inch and that its diameter should be .8 of an inch or less.

Accordingly, the connector cord which completes the circuit between such earphone and the other elements of the hearing aid should be very thin and flexible, and it must be so connected to the earphone as to withstand the strain imposed thereon when the user pulls the cord. Furthermore, since such cords deteriorate and become unsanitary inuse. they should be readily exchangeable. Accordingly, a detachable circuit connection must be provided between such cords and the elements of the hearing aid to which they are connected.

Many efforts have been made in the past to devise an electrical connector suitable for use in such midget earphones, and similar hearing aid elements. The electrical connector of the invention is of much simpler construction thanlthe best prior electrical connectors used in similar applications and embodies various desirable novel features which facilitate the manufacture and assembly of such connectors and which make it possible to render them much more compact.

Although the electrical connector of the invention hasmanyother applications outside the hearing aid ileld, it will be described in connec- 1 tion with its application to a midget earphone forming part of a h'earing,aid. I As shown in Fig. 1, such midget earphone It worn either directly within the lobe of the ear or on an ear tip molded to fit the ear, in the way in a casing shell 24 made, for instance, of a syn- H thetic resin molding.

The circuit between the energizing leads 25 of the driving structure 2| to the cord leads 22 is completed by detachable connectors, each formed by a bushing jack 26 held in a wall of the receiver casing 24 and a plug member 21 secured to the end of the cord lead 22 and detachably engaging with the bushing jack 26.

In order tosecure foolproof operation of such hearing aid, it is essential that the detachable connectors, which complete its operating circuits, shall assure good electrical circuit connections and at the same time shall be mechanically strong so as to withstand the strain to whichthey I are.subjected, for instance, when the user pulls the cord lead to disconnect the cord from the earphone.

Accordingly, the electrical connectors completing the connections to the circuit elements housed within the tiny receiver casing 24 must provide not only suflicient electrical conduction across the contact surface, but also must maintain the contact engagement and connection with sufllcient mechanical force to prevent breaking of the contact engagement by the forces to which the lead is exposed in the course of ordinary use.

The plug-jack connector of the invention, different forms of which are shown in the drawings, is mechanically extremely simple and strong and electrically very efficient while being kept so small that it does not add any bulk to the structure of the unit, such as the earphone, with which it is associated.

As shown in detail in Figs. 4 and 5, the jack 26 is constructed in ,the form of a very short cylindrical bushing extending through a hole in a relatively thin wall portion 28 of the casing. The outer end of the bushing jack 26 is provided with a flange 3| fitting within a recess 23 of the wall opening. The portion of the bushing jack 26 extending inwardly from the flange 3| is split Iongitudinally at 32 to form two jaws or prongs 33 for making contact engagement with the shank of the plug 21. Since the jack 26 is placed within the casing wall, it may be longitudinally split down to its flange 3| so as to assure that the jaws of the bushing so formed shall flex freely and make engagement with the shank of the plug 21.

' Alternatively, the jaws 33 of the jack may be made in the form of two separate members.

' A leaf spring 34 is split along its middle to provide two flat arms having arcuate prong-shaped end portions 35 shaped to interlockingly engage laterally protruding interlocking elements formed .34 which locks and retains the Jack 26 in its operative position within the casing wall 26 is also utilized to exert the spring pressure for pressing the jack jaws 33 into contact engagement with the shank of the plug member 21. Accordingly, such externally compressed split jack bushing connection to the plug provides a much better electrical connection than a mere contact point, such as'is afforded by the ordinary-jack spring which presses on one side of the plug member.

In addition, the combined locking and contact pressure exerting action of the leaf spring 34 assures that no stress is transmitted from it to any part of the housing wall since the two Jaws 33 of the jack 26 take up the entire spring stress exerted thereon by the leaf spring 34. All these advantages are secured with a thin leaf spring 46 having a thickness of only .015 inch or less and a width substantially equal or only negligibly larger than the diameter of the Jack 26.

At the sam time, the electric element, such as the driving structure 2| of the receiver, may be quickly detached from the inner end of the jack 26 without unsoldering operations, because it is merely necessary to pull off the flat spring member 34 from the inner end of the jack jaws 33. The complete assembly of the jack 26 consists merely in dropping the Jack 26 into the hole of the casing wall '23 andsnapping the end of the leaf spring 34 into its inner locking'slot 32 at its inner end. Once mounted in the hole of the wall 23, breakage of the outer flange of the Jack on the recessed inner end 36 of the jack 26 at the point where it emerges from the hole in the easing wall 26, so as to press the Jack jaws 33 against the plug 21 and assure a good electrical contact cally very strong against bending forces acting in the plane of its arms 35, a very short leaf spring will not impair its operation because the facing side edges 36 of its Jaws 33 will be kept in their proper operating position by the spring 34.

In Figs. 6 to 8 is shown another form of detachable connector jack of the invention. The jack bushing 40 has an outer flange 4| and asplit portion extending from the flange through the hole in the casing wall 23 and forming two jack jaws 43, as in the bushing jack of Figs. '4 and 5. The two jaws 43 of the bushing are held in the hole of the wall 23 and are pressed inwardly into contact engagement-with the shank of plug 21 by a short coil spring 44 interlockingly engaging laterally protruding interlocking elements formed on the recessed inner end portion 46 of' the-bushing 40 at the point where it emerges from the casing wall 26.

A spring 44 made of two-turns of music wire about .020 inch in diameter wound into a coil approximately of an inch in diameter was found reliable and efficient in the practical embodiment of the invention. The locking groove 45 of the jack 40 is tapered outwardly towards the adjacent inner surface of the casing wall 26, and the inner turn of the coil spring 44 is seated in the deep portion of the groove 46 so as to hold on the outwardly tapered portion of the groove the adjacent outer spring turn and cause it to exert on the jack laws 43 inwardly directed forces maintaining good contact engagement between the iaws and the shank of the plug member, while at. the same time holdingthe bushing firmly in the casing wall 28.

The end of the spring coil 44 extending along the casing wall is made somewhat longer, as indicated at 44, and serves as the soldering junction on the bushing 40.

As shown in Fig. 6, the groove 45 is made wide enough for only one turn of the coil so that the other outer turn ofthe coil is pressed outwardly to exert inwardly acting forces around the tapered end portion of the groove. The coil spring 44 performs thus all the functions of the leaf spring 34 used in the connector of Figs. 4 and 5, and makes it possible to provide an even mor compact connector unit.

I As shown in Fig. 6, a washer 41 of wear-resist- 3 Zi'hisarrangementmakes it possible to assure a hermetic moisture-proofseal for the interior of the casing, for instance, by coating the inner wall surface 59 of the casing wall 50 and the adjacent surface of the closure wall 51 with a .coating of waterproof material, such as Vinylite.

In Figs. 12 to 16 is shown how a connector of Y the type described in connection with Figs. 4 to 8 may be utilized in conjunction with a tiny multiterminal plug connector of a wearable hearing aid of the type described, for instance, in the copending application Ser. No. 294,649, filed September 13, 1939, assigned to the assignee of the present application. The plug is formed of a casing 6| having cavities 62, 63 which are closed by a closure plate 84- held clamped to the plug casing by screws 85 engaging suitable inwardly:

' threaded bushing inserts embedded in the molding material, such as metal, may be placed on the inner surface of the casing wall underlying the outer portion of the spring coil 44 so as to distribute its pressure over a large surface portion of the casing wall against which it is held. The extension 46 of the coil spring which serves as an electrical soldering connection to the bushing 44 can be made very short, only about V. of an inch long. The leaf spring 24 of the arrangement of Figs. 4 and 5 has to be made somewhat wider and about of an inch longer'so as to secure sufficient flexibility and amplitude of deformation of its spring arms 35. The connector bushing with the coil springs shown in Figs. 6 to 8 may thus. be designed to be more compact than the connector of Figs. 4 and 6.

'Another way of arranging connectors of the type illustrated in Figs. 4 and 5 in the casing wall of a unit, such as an earphone, thatis small enough for wear within the earlobe of the user, is shown in Figs. 9 and 10. The rear wall 50 of an earphone shown in Fig. 11 has an outwardly bulging housing projection I with a transversely extending wall portion 52 provided with two holes in which connector bushing jacks 28, similar to those of Figs. 4 and 5, are mounted. I

The bushings 26 are held in place in the transvers wall portion I2 by longitudinally split leaf springs 54, each having two arcuately-shaped prong-like end portions 5! locking and engaging the inward ends of the jaws 23 of the bushing 26, as in Figs. 4 and 5. The leaf springs I4 of the arrangement shown in Figs. 9 to 11- have their prong-like end portions II angularly bent relatively. to the mid portion which is secured, as by rivet N, to a closure plate I! which may be secured, as by a screw ll, over the inward opening of the cavity formed in the cover projection Terminal lugs held under the heads of the rivets ll serve as soldering connections to the leads 2! of the driving unit of 'the'receiver. The

two angularly bent leaf springs I4 are so arranged on the closure plate ll that on pushing it inwardly, the, prongs N are automatically ed body of the casing.

In the cavities 82 of the plug casing are held a plurality of plug members 66 to the inward ends of which are connected the ends of cord leads I! of a multi-lead connecting cord. In the two outer cavities 83 of the casing are mounted two plug-jack members I0 having, in the form shown. a downwardly projecting plug shank H and an upwardly extending jack 12, the intermediate portion of the plug-jack member 10 forming a substantially rectangular anchoring block fitting within an anchoring cavity 68 formed at the junction faces of the plug casing 61 and its closure wall 64 in theway shown in Figs. 12, 13 and 15. The jack portion is formed by longitudinally slittinga cylindrical bushing portion extending from the anchoring member 10 so as to provide two jack jaws l2 shaped to make contact engagement with the shank of a plug member 21 connected to the end of a cord 22, extending, for instance, from a receiver. As shown in Fig. 14, the exterior surface of the jack jaws 12 has formed therein extremely shallow annular grooves 13 in which is held a two-turn coil spring 44, similar to the coil spring 44 of Figs. 6 to 8, so as to press inwardly the jaws 12 into contact engagement with the plug shank 21.

As pointed out above, a coil spring 44 formed I of two turns of a high grade spring metal wire,

the plug 21 and retain it in its inward position.

Although such small coil spring exerts sufficient force to retain the plug in its contact engagement within the jack,.such spring becomes permanently deformed if the spring wire is stretched brought into engagement with the grooves 36 of the two jacks 28' and locked in place so as to retain them in their position within the wall casing portion 62 and to exert on the jack laws inwardly directed forces assuring good contact engagement with the shank of the cord plug 21 On removing the closure wall I1 from its position, the two bushings 26 are released.

beyond its elastic limit.

' In order to eliminatethe possibility of such deformation of the spring and at the same time secure a very positive electrical as well as mechanical engagement of the plug shank with the jack, the shank of they plug 21 is provided at its end with a generally ball-shaped tip 14 which is only a few thousandths of an inch larger than the shank and the inner diameterof the opening between the jack jaws so that when the-plug tip 16 is pushed inwardly, the forces imparted by the ball-shaped plug tip 16 will not subject the coil spring 44 to stretching forces exceeding Hookes limit. With a coil spring 44 of the dimensions described above, it was found that the inner diameter of the spring may be in- '7a creased by .003 of an inch without subjecting it to signed with plug shanks having a protrusion of v a thickness between about one to eight percent greater than the thickness of the plug shank.

making it possible to provide the plugs with very short shanks, since the ball-shaped tip ll of the shank assures good mechanical engagement of the plug with the Jack, the plug shank being made only sufficiently long to keep the plug straight in the jack and assure a good electrical,

connection between the jack and the plug. As shown in Fig. 14, the inner surface portions of the Jaws 13 between which the ball tip 18 of the plug 21 is engaged, is given a generally spherical contact surface.

In all of the plug-Jack arrangements described above, the spring which engages the exterior of the jack jaws extending on the opposite sides of the plug shank is made to exert pressure on the laws, which in turn is exerted on the plug.

As shown in Figs. 17 to20, the invention resides also in an improved construction and arrangement of the plug and its connection to the cord which makes it possible to reduce the bulk of the ,plug to a fraction of the best prior plugs, and

protects the junction between the cord and the plug against damage incident to bending the cord relatively to the plug, whileat the same time assuring a good mechanical and electrical connection between the conducting portion of the cord lead and the plug as well as good external appearance of the cord plug connection.

The body of the plug 21 from which the ballshaped shank 18 extends is of generally cylindrical form and has a cavity 8| in which the end of the cord lead 22 is held after it is flrst prepared 3,889, 1&6

ping connection is established between all the elements of the cord lead and the body of the imparts to the plug a permanent deformation,

in the way shown in Fig. 18. In preparing the cord lead 22, a rectangular piece of sheet metal I! is folded over a portion of the lead and clamped thereover, the sheet metal clip 82 having punched therein holes 83 so as to provide gripping projections which grip the exterior surface of the lead cover 82.

Such flexible cordlead is usually composed of a core consisting of a plurality of intertwisted flexible tinsel-like filaments 84 of highly conducting material, such as copper, and the core is covered by a covering 85 of flexible insulating material, such as suitably woven silk threads, ,ar-

' ranged to thoroughly protect the conducting core and at the same time carry the strain imposed on the leads when it is being pulled in use.

The clip 82 is clamped a short distance, about of aninch, from the end of the lead. The portion of the insulation covering 85 which extends beyond the end of the clip I! is then stripped oil, as by a razor, so as to expose fliaments of tinsel in the way shown in Fig. 18, The tinsel filaments 84 are then folded over the exterior of the conducting metallic clip 82 and inserted within the cavity 8| of the plug body 21. 'I'hereupon, the rear portion of the cylindrical plug member 21 is placed in a tool formed, for

instance, of two clinching members 88 while the plug is being rotated so as to deform the end portion of the cylindrical plug cavity into an annular groove while at the same time giving the edge portion 81 of the cavity walls an outward taper, in the way shown in Fig. 20. This construction assures that a very intimate and good'electrical connection as well as a positive mechanical gripand the clamping stress is distributed along the entire length of the cord lead which is clamped within the clip 82. In addition, the tinsel is flrmly clasped between the clip and the interior cylin drical surface of the plug cavity, thus securing a good electrical connection.

By forming the clamping groove 88 in the cord junction cavity of the plug, the cavity wall of the plug is automatically given an outwardly tapering semi-conical opening which eliminates any tendency to impose cutting stresses on the cord covering at the point where it leaves the plug cavity.

tn the cord and plug arrangement described above, each part of the connector Jack and connector plug is proportioned to carry a large, but safe, stress. Each portion performs at least one necessary function and in some cases several simultaneous functions. At the same time, all connector elements are made extremely small and compact. For instance, in the practical construction of such plug connectors, the largest outer diameter of the plug may be made as little as .080 of an inch or less while assuring a good mechanical and highly conducting electrical connection between the cord lead and the plug.

Various other modifications of the invention will suggest themselves to those skilled in the art. It is accordingly desired that the appended claims be construed broadly and that they shall not be limited to the speciflc details shown and 'through between the two sides thereof; a generally tubular jack structure having a lateral extension element on its outer and shaped for interlocking engagement with the outer side of said wall to limit inward movement of said jack and at least two facing flexible Jawsextending into said hole for engaging the opposite sides. of a plug inserted from the outer end of said jack; said jaws having inner Jaw portions exposed on the inner side of said wall; the exterior of the exposed inner jaw portions having formed thereon laterally extending interlocking elements; and a metallic spring member held in interlocking engagement between the inner side of said wall and the interlocking elements of said inner Jaw portions so as to hold said jack flxed in its operative position within said wall; said spring member having an elastically deformed portion-embracing said exposed inner Jaw portions and exerting inwardly directed restoring forces on the opposite sides of said laws for maintaining intimate electrical and ilrm mechanical connections beextension element on its outer end shaped for interlocking engagement with the outer side of said wall to limit inward movement of said jack and at least two facing flexible jaws extending into said hole for engaging the opposite sides 01 a plug inserted from the outer end of said jack; said jaws having inner jaw portions exposed on the inner side of said wall; the exterior of the exposed inner jaw portions having formed thereon laterally extending interlocking elements; and a metallic leaf spring member held in interlocking engagement between the inner side of said wall and the interlocking elements of said inner jaw portions so as to hold said jack fixed in its operative position within said well; said leaf spring member being provided with an elastically deformed portion having two arms embracing said exposed inner jaw portions and exerting inwardly directed restoring forces on the opposite sides of said jaws for maintaining intimate electrical and firm mechanical connections be-- tween said spring member, said jack and a plug inserted into said jack.

3. In an electrical connector arrangement: a supporting wall having'a hole extending therethrough between the two sides thereof; a generally tubular Jack structure having a lateral extension element on its outer end shaped for interlocking engagement with the outer side of said wall to limit inward movement of said jack and at least two facing flexible jaws extending into said hole for engaging the opposite sides of a plug inserted from the outer end of said jack; said jaws having inner jaw portions exposed on the inner side of said Well; the exterior of the exposed inner jaw portions having formed thereon laterally extending interlocking elements; and a metallic coil spring member held in interlocking engagement between the inner side of said wall and the interlocking elements of said inner jaw portions so as to hold said jack fixed in its operative position within said wall; said coil spring member being provided with an elastically deformed portion having at least one coil tum embracing said exposed inner jaw portions and exerting inwardly directed restoring forces on the opposite sides of said jaws for maintaining intimate electrical and firm mechanical connections between said spring memher, said jack and a plug inserted into said jack. 4. In an electrical connector arrangement: a

supporting wall having a hole extending therethrough between the two sides. thereof; a generally tubular jack structure having a lateral extension element on its outer end shaped for interlocking engagement with the outer side of said wall to limit inward movement of said jack and at least two, facing flexible jaws extending into said hole for'engaging the opposite sides of jaws for maintaining intimate electrical and firm mechanical connections between said spring member, said jack and a plug inserted into said jack.

ment: a supporting wall having a'hole extending therethrough between the two sides thereof; a generally tubular jack structure having a lateral extension element on its outer end shaped for interlocking engagement with. the outer side of said wall to limit inward movement of said jack and at least two facing flexible jaws extending into said hole; a plug of conducting material having an elongated shank for insertion through the outer end of said jack into engagement with said jaws; said jaws having inner jaw' portions exposed on the inner side of said wall; the exterior of the exposed inner jaw portions having formed thereon laterally extending interlocking elements; and a metallic portions and exerting inwardlydirected restoring forces on the opposite sides of said jaws for'maint'aining intimate electrical and firm mechanical connections between said spring member, said jack and said plug; said shank having a generally-annularly shaped protrusion 01' a thickness between about one to about veight percent greater than the thickness of the shank and said elastically deformed spring portion being so designed and its cross-section being so proportioned as to prevent permanent deformation of said spring portion by the expanding forces exerted thereon when the protrusion of the plug is moved past the jaw portion embraced by said spring portion.

6. In an electrical plug connector arrange-.

ment: a supporting wall having a hole extending therethroughbetween the two sides thereof; a generally tubular jack structure having a lateral extension element on its outer end shaped forinterlocking engagement with the outer side of said wall to limit inward movement of said jack andat least two facing flexible jaws extending into said hole; a plug of conducting material having an elongated shank for irmertion through the outer endof said jack into engage ment with said jaws; said jaws having inner jaw portions exposed on the inner side of said wall; the exterior of the exposedv inner jaw portions havingformed thereon laterally extending ;-in-

. terlocking elements; and a metallic leaf spring a plug inserted from the outer end' of said jack;

said jaws having inner jaw portions exposed on the inner side of saidwall; the exterior of the exposed inner jaw portions having formed thereon laterally extending interlocking elements; and a metallic coil spring member held in interlocking engagement between the inner side of said wall and the interlocking elements of said inner jaw portions so as to hold said Jack fixed in its operative position within said wall; said coil spring member being provided with at least two coil turns embracing said exposed inner jaw portions and having at least one elasticalb' deformed coil turn exertinginwardly directed restoring forces on the opposite sides of said member held in interlocking engagement be,- tween "the inner side of said wall and the interlock ng elements of said inner jaw portions so as to hold said jack fixed in its operative position within said wall; said spring member be-. ing provided with an elastically deformed portion having two arms embracing said exposed inner jaw portions and exerting inwardly directed restoring forces on the opposite sides of said jaws for maintaining intimate electrical and firm mechanical connections between said spring member, said jack and said plug; said shank having a generally-annularly shaped pro-5"" 'trusion of a thickness between about one ,to

about eight vpercent greater than the thickness of the shank and said elastically deformed spring portion being so designed and its cross-section 5. In an electrical plug connector arrangeposed on the inner lateral extension element on its outer end shaped for interlocking engagement with the outer side of said wall to limit inward movement of said jack and at least two facing flexible jaws extending into said hole; a plug of conducting material having an elongated shank for insertion through the outer end of said jack into engagement with said jaws; said jaws having inner jaw portions exposed on the inner side of said wall; the exterior of the exposed inner jaw portions having formed thereon laterally extending interlocking elements; and a metallic coil spring member held in interlocking engagement between the inner side of said wall and the interlocking elements of said inner jaw portions so as to hold said jack fixed in its operative position within said wall; said spring member being provided with an elastically deformed portion having at least one coil turn embracing said exposed inner jaw portions and exerting inwardly directed restoring forces on the opposite sides of said jaws for maintaining intimate electrical and firm mechanical connections between said spring member, said jack and said plug; said shank having a generallyannularly shaped protrusion of a thickness ,between about one to about eight percent greater thanthe thickness of the shank and said elastically deformed spring portion being so designed and its cross-section being so proportioned as to prevent permanent deformation of said spring portion by the expanding forces exerted thereon when the protrusion of the plug is moved past the jaw portion embraced by said spring portion. v

8. In an electrical connector arrangement: a supporting wall having a hole extending therethrough between the two sides thereof; a generally tubular jack structure having a lateral extension element on its outer end shaped for interlocking engagement with the outer side of said wall to limit inward movement of said jack and a? least two facing flexible jaws extending into said hole for engaging the opposite sides of a plug inserted from the outer end of said jack; said jaws having inner'jaw portions exside' of said wall; the exterior of the exposed inner jaw portions having formed thereon laterally extending interlocking elements; and a metallic spring member held in interlocking engagement between the inner side of said wall and the interlocking elements of said inner jaw portions so as to hold said lack fixed in its operative position'within said wall; said spring member having an elastically deformed spring portion embracing said exposed inner jaw portions so as to resist outwardlydirected expanding forces and exert inwardly directed restoring forces on the opposite sides of said jaws for maintaining intimate electrical and firm mechanical connections between said spring member, said jack and a plug inserted into said jack; said spring member being-so shaped and arranged relatively to the jaw portions engaged thereby that outwardly directed expanding forces exerted by said jaw portions cause said spring portion to be deformed in the direction in which it exerts substantially maximum deformation-resisting forces.

9. In an electrical plug connector arrangement: a supporting wall having a hole extending therethrough between the two sides thereof a generally tubular jack structure having a lateral extension element on its outer end shaped for interlocking engagement with the outer side of said wall to limit inward movement of said jack and at least two facing flexible jaws extending into said hole; a plug of. conducting material havin an elongated shank for insertion through the outer end of said jack into engagement with said jaws: said jaws having inner jaw portions exposed on the inner side of said well; the exterior of the exposed inner jaw portions having formed thereon laterally extending interlocking elements; and a metallic spring member held in interlocking engagement between the inner side of said wall and the interlocking elements of said inner jaw portions so as to hold said jack fixed in its operative position within said well; said spring member being provided with an elastically deformed spring portion enbracing said exposed inner jaw portions and exerting inwardly directed restoring forces on the opposite sides of said jaws for maintaining intimate electrical-and firm mechanical connections between said spring member, said jack and said plug; said spring member being so shaped and arranged relatively to the jaw portions engaged thereby that outwardly directed expanding forces exerted by said jaw portions cause said spring portion to be deformed in the direction in which it exerts substantially maximum deformation-resisting forces; said shank having a generally annularly-shaped protrusion of a thickness slightly greater than the thickness of the shank; the thickness of said protrusion being so chosen in relation to the thickness of the shankand said elastically-deformed spring portion and its cross-section being so designed and proportioned as to prevent permanent deformation of said spring portion by the expanding forces exerted thereon when the protrusion of the plug is moved past the jaw portion embraced by said spring portion.

10. In an electrical plug connector arrangement: a supporting wall having ahole extendtending of; a generally tubular jack structure having a lateral extension element on its outer end shaped for interlockingengagement with the outer side of said wall to limit inward movement of said jack and at least two facing flexible jaws exinto said hole; a plug of conducting material having an elongated lshank'for insertion through the outer end of said'jack into engagement with said jaws; said jaws having inner jaw portions exposed on the inner side of said wall; the exterior o f'the exposedinner jaw portions having formed'thereon laterally extending interlocking elements; and a metallic spring member held in interlocking engagement between the inner side of said wall and the interlocking elements of said inner jaw portions so as to hold said jack fixed in its operative'posi tion within said wall; said spring member be ing provided with an elastically deformed spring portion embracing said exposed inner jaw portions and exerting inwardly directed restoring forces on the opposite sides of said jaws for vmaintaining intimate electrical and firm mechanical connectionsibetween said spring memher, said jack and said plug; said spring memsaid protrusion being so chosen in relation to bet being so shaped and arranged relatively to the thickness of the shank and said elasticallythe j w portions engaged thereby that outw d y deformed spring portion and its cross-section directed expanding forces exerted by said Jaw being so designed and proportioned as to preportions Ca s Sa d Sp portion to be deformed 5 vent deformation of said spring portion by the in the direction in which it exerts substantially expanding forces exerted thereon when the promaximum deformation-resisting forces; said trusion of the plug is moved past the jaw porshank having a generally annularly-shaped protion embraced by said spring portion.

trusion of a thickness of the order of between about one to about eight percent greater than 10 RICHARD W. CARLISLE. the thickness of the;shank; the thickness of ALFRED J. MASTROPOLE. 

